reptile0009 asked: When is fan service (i.e. big breasts and panty shots) acceptable in a comic?
There is no hard-set “rule” about “acceptability.” The problem, as I have said to you before, is a matter of how much there is of it, not that it exists at all.
That being said, panty shots of underage girls is a no-no.
If, thematically, it makes sense for your comic to have sexy ladies being sexy at this part of the scene, then it is appropriate.
For example, if you have a theme of fertility or general sexiness going on, it is hella appropriate, and in fact would be weird to have a lack of fanservice.
If you have a scene where a character (male or female!) is trying to sexify themself up, or where their being a total sexy monster* is a really important facet of what’s going on, it is absolutely appropriate.
If, however, your comic and/or scene is focused on something dramatic, tragic, cute, mundane, and/or otherwise nonsexual, LAY OFF THE DAMN T&A JEEZ IT WILL NOT KILL YOU TO DRAW PEOPLE AS JUST PEOPLE AND NOT BONER FACTORIES FOR ONCE.
(As an aside, big tits are not inherently fanservicey or sexual, and it’s not really cool to treat a character with big tits as automatically either of those things. If you are comicking with the idea of “well she has big ol’ tittays so OBVIOUSLY she is going to be showing them off and flingin’ ‘em around so we hetero mens and I guess lesbians can enjoy it!” then you are doing it wrong.**
* Metaphorically speaking, though I do not discount the option of monsters also being sexy.
** Please note this is not discounting the possibility of boobie ladies who would do such, merely explaining that not all of them would and it is not an inherent trait that appears in ladies with higher than a D cup.